Upgrade `prisma` and `@prisma/client` to latest version

[alexkramer98]

I'd like to use new features introduced after 6.1.0. I tried to update the dependencies in #99 but the build is failing.

[sibbl]

It's not only about new features, but e.g. npx prisma generate fails with the 6.16.x versions:

Error: 
Cannot find module '/Users/xyz/source/repos/digitax/digitax/node_modules/@prisma/client/runtime/query_engine_bg.postgresql.wasm-base64.js'
Require stack:
- /Users/xyz/.npm/_npx/2778af9cee32ff87/node_modules/prisma/build/index.js

This is tracked here: prisma/prisma#28076

The workaround to use npx prisma@6.15.0 generate works so far.